Rock drill



Patented June 22, 1943 'rear OFFICEV solaires. r(ci. 287-126)V n Y 'able bitV rock drill having interlocking surfaces This invention relates te the type of rock-drill in which the cutting end .o-r bit isv detac-hably mounted upon the end of the drill rod and in which the securing of the bit on the drill rod shank is accomplished by a rotative movement. i

The principal object of the present invention is to utilize the end thrust impar-ted to thedrill rod by the drilling machine to effect the relative rotation cf the bit to cause the bit to tighten into locking engagement with the shank.

The principal feature off the invention consists in forming the end surface of the drill rod or shank and the-engaging end surface of the drill bit with corresponding spiral surfaces, which,

under the impact blows of the drill, will cause the bit to rotate relative to the drill rod a part revolution in a direction opposite to the direction of rotation of the `drill rod as imparted by the drill mechanism and tol effect the locking engagement of the peripheral surface of the drill rod with the surrounding sleeve portion of the bit.

This invention is particularly applicableto the type of drill in which the interlocking engaging surfaces of the bit and drill rod are formed with 25 an Archimedes spiral contour so that relative rotation of the bit and drill rod or shank causes the intimate engagement of the decreasing radius surface of one member with the increasing radius surface of the other member to effect a secure interlock and uniform contact for the transmission of impact shocks.

In the accompanying drawing Figure l is an elevational view of an assembled drill bit and shank. Y

Figure 2 is. a sectional viewvof the improved drill bit showing the shank en d ofthe drill rod inserted therein in elevation. y

Figure 3 is an enlarged perspective detail of the end extremity of the drill illustrating my improvement.

Figure 4 is an enlarged elevational detail of the extreme end of the improvedr drill rod and showing it inserted within the socketeddrill bit.

Figure 5 is an end View of the drill bit illustrating diagrammatically the relation between the Archimedes spiral perimeter of the shank and the spiral end surface.

Figure 6 isa perspective view of a bit embodying the present invention, the skirt or spirally surfaced sleeve portion being broken away to expose the spiral end contact surface forming the socket bottom.

It has been effectively demonstrated in practical mining operations that the type of removion of an Archimedes spiral formation.arev verygpractical andthe interlock o f. the Archimedes spiral surfaces isvery dependable.

It has been found desirable however to facilitate the work of the miner in placing the bit on the end of the shank. Itis of course understood that in underground operations the miners are working under extreme circumstances, in that -in most cases they operate entirely under the beams of small helmet lamps..A Consequently it isdesirable that the miner be assisted as greatly as possible in the placing of removable` drillbits on the end of the drill. shank with the least possible effort and where the bit and. shank are formed with Archimedeslspiral interlocking surfaces the practice has been to form the intertting surfaces .with a'rather close.. range. That is` to say, the bit hadto be turned carefully to a fairly accuratepositionin relation tothe shank in order to place the bit onthe shank. f'

According to the presentinvention the dimensions of the Archimedes spiral. of the shank, are related to the dimensions of the intertting Archimedes-spiral of thev bit socket so that, the bit andi shank willl be relatively loose whenr they are placed together andV there willbe a latitude of operation or turningv relationship between the two of approximately oneA half an inch before they definitely engage in .locking contact, though this latitude is not arbitrary, but with approximately one half anY inch clearance in the turning relationship of the drill and bit. it becomes a comparatively simple matter for the miner to place the bit on the end ofthe drill shank quite easily, and then by turning the bit the bit and shank are interlocked.

It is found desirable to ensure the positive interlock of the Archimedes spiral surfaces other than through the voluntary action' of the miner after he has placed the bit on the end of the shank and inorder to accomplish the desired result the'end face ofthe shank is formed with a spiral inclined surface. This is very clearly illustrated in the accompanying drawing.

The shank i of the drill rod 2 hasY its periph.- eral surface cut with an Archimedes spiral which is particularly illustrated in Figures 3 and 5. The end surface 3 is formed in a flat spiral formation having an incline of approximately one-sixteenth of an inch as between the highest point 4 and the lowest point 5.

The dimensions are approximately correct as shown in Figure 2 but of course are exaggerated in Figures 3, 4 and 5.

The inner peripheral wall 6 of the socket of the bit member 1 is formed with an Archimedes spiral coinciding substantially with the Archimedes spiral of the shank l but the internal dimensions of the socket in relation to the external dimensions of the shank are such that the bit will rotate approximately one half an inch before the surfaces engage in locking contact. This is illustrated in exaggerated dimensions in Figure 5.

The bottom face l' of the socket is shaped to coordinate with the end face of the shank I, it having a at shallow spiral of corresponding dimensions.

It will be readily understood that in placing the bit on the end of the shank the socket portion is slipped over the shank end with the offset portion 8 of its surface connecting the extremities of the Archimedes spiral closely adjacent to the corresponding offset portions 9 of the shank. The bit is then quite loose onvthe shank but a slight turn, say of a quarter of an inch or better, f will bring the surfaces of the Archimedes spiral into contact sufficient to hOld the bit in place.

When the bit is then pressed against the rock which is to be drilled pressure is applied and the drill rod is rotated. The applied pressure forces the spiral end surface of the drill shank into engaging contact with the spiral bottom surface of the bit and the natural tendency is for the two engaging sloping surfaces to rotate the one on the other. This rotation of course rotates the entire bit, and the inner peripheral Archimedes spiral surface is forced into snug locking engagement with the Archimedes spiral surface of the shank, and the rotating force is sufficient to create a pressure fit.

It will of course be understood that as the bit member is formed by a forging operation and it is handled while hot the skirt or circumferential wall of the bit may be slightly deformed. The slackness of t between the bit and the shank permits the shank to be readily engaging contact completely around the shank.

The manufacture of the shanks and bits in the manner described enables the operator to place the bit in position with much greater ease than if bits and Shanks were made a close fit and because of the spiral end planes being engaged under vibrating pressure it is only necessary for the operator to give the bit enough twist to hold until it comes into contact with the rock face, after which it is driven into tight sealing contact so that the bits will not become dislodged from the shank.

The improvement herein described as applying a spiral surface to the end of the shank and the surface of the bit engaging therewith is herein applied to bits having locking engagement through the medium of Archimedes spiralshaped surfaces but it will be understood that the adaptation of an end spiral contact may be utilized in any other type of bit which requires to be turned in relation to the shank to secure it in place,

What I claim as my invention is:

1. A rock drill, comprising in combination, a socketed bit, a drill rod having its perimeter formed to engage in locking contact with the wall of the socket of the bit through relative rotation of the rod and bit, the end of the rod having a flat spiral contact face and the bottom of the bit socket having a corresponding flat spiral contact face adapted to cause relative rotation of the bit upon the application of impact shocks to the rod to effect the locking of the perimeter.

2. A rock drill, comprising a drill rod having the perimeter of its extremity formed 'with an Archimedes spiral surface and having a spirally inclined end face, and a bit having the inner wall of its socket formed with an Archimedes spiral surface to engage in locking contact with the perimeter of the rod, the bottom of the socket being formed with a spiral surface to engage `the spiral end of the rod and adapted upon the application of impact shocks to the rod to effect the turning of the bit to bring the two Archimedes spiral surfaces into locking engagement.

3. A rock drill, comprising a drill rod and a detachable bit, the rod and bit having interlocking cam-like peripheral surfaces, the bit being formed to slip loosely over the end of the rod and adapted to be turned to interlockingly engage said cam-like surfaces, the end of said rod having a spirally inclined surface and the bottom of the bit socket having a correspondingly shaped spirally inclined surface to that of the rod adapted to maintain a continuous end contact with the rod and to effect turning of the bit on the rod on the application of impact shocks to the rod to urge said camlike peripheral surfaces into tight interlocking relation.

4. A rock drill, comprising in combination, a socketed bit, a drill rod having its perimeter formed to engage in locking contact with the wall of the bit socket through relative rotation of the rod and bit, and means enclosed within the bit socket adapted to effect relative rotation between the rod and bit upon the application of impact shocks to urge the interlocking peripheral surfaces of the rod and bit into locking engagement,

5. In a rock drill, the combination of a drill rod having an inclined surface on its end face and an eccentric periphery, and a detachable socketed bit having an eccentric inner wall to 

